Transformer switching arrangement



July 7, 1936. H. R. TURNER TRANSFORMER SWITCHING ARRANGEMENT 3Sheets-Sheet 1 Filed Oct. 9, 1934 Fi gl.

is Attorney.

July 7, 1936. 1-1. R. TURNER 2,046,979

TRANSFORMER :SWITCHING ARRANGEMENT Filed Oct. 9, 1934 3 Sheet-Sheet 2Fig. 2.

Inventor Harold R Turner.

is Attorney July 7, 1936. H. R. TURNER TRANSFORMER SWITCHING ARRANGEMENT3 Sheets-Sheet 5 Filed Oct. 9, 1934 m nun-v11,

lnventov Havold R Turner,

g Attorney.

c m 7/4 iiTill W Patented July 7, 1936 UNITED STATE TRANSFORMERSWITCHING ARRANGE- MENT Harold R. Turner, Pittsfield, Mass, assignor toGeneral Electric Company, a corporation of New York Application October9, 1934, Serial No. 747,520

18 Claims.

My invention relates to improvements in transformer switchingarrangements and more particularly to improvements in arrangements forconnecting transformers to feeders, grounding transformers and feedersunder predetermined conditions and changing the transformation ratio. Anobject of my invention is to provide an improved transformer switchingarrangement which, with minimum space and insulating fluid requirements,insures maximum safety and accessibility without greatly increased cost.

Transformers used in secondary network systems are usually placed invaults which are frequently located in buildings. Such transformers havebeen provided with junction boxes mounted on the outside of thetransformer casing and the feeder connections led inthrough the floor ofthe vault to the junction box. The junction box contained theconnections for the feeder, usually a cable, and these connections wereaccessible only upon removal of the junction box cover and theinsulating liquid. The junction box sometimes contained a switch forgrounding the transformer under predetermined conditions. In order toprevent operation of the grounding switch while the transformer isenergized, an electromagnetically controlled lock was provided, theelectromagnet being mounted either in the junction box or in thetransformer where it was not only not readily accessible but also was anelectrical hazard. The transformers have also been provided with ratioadjusters. In order to prevent operation of the ratio adjusters whilethe transformer was energized, there has been provided over the ratio 85adjusting switch handle a cover which could not be removed unless thegrounding switch was in the grounding position. This arrangement was notentirely satisfactory because the ratio adjusting switch could be leftin an off-tap posi- 40 tion and the grounding switch operated at will.Oil was used as an insulating and cooling fluid and the transformer andjunction box required a large volume of oil. Obviously, the fire andexplosion hazards placed many structural limita- 45 tions on both thelocation and construction of the vaults. These limitations-were notconducive toeither simplification of structure or convenience inlocation of the vaults.

In order to insure greater safety from explosions and fire, there hasbeen'developed a noninfiammablc. and non-explosiveinsulating liquidcomposed of certain halogenated hydrocarbons.

But the cost of this is so much greater than the cost of oil as torender its use practically pro.- 55 hibitive in the prior transformerswitching arrangements because of the great volume of insulating liquidrequired by the transformer and junction box. In order to take advantageof the safety features of this insulating liquid with the greatesteconomy and simplification in struc- 5 ture, I provide, in accordancewith my invention, an improved transformer switching arrangement inwhich the feeder connections, grounding switch and ratio adjustingswitch are all mounted within the transformer, thereby eliminating thejunc- 10 tion box and the space required by it in the vault, as well asthe insulating liquid necessary to fill it. Further, by a more compactarrange- I ment of parts, the volume of the transformer itself isreduced. Also in accordance with my 15 invention, I so arrange thefeeder connections and the grounding switch as conveniently to arrangefor bringing the feeder into the vault 'near the ceiling and as to beaccessible for inspection and maintenance of those parts most likely to20 need attention or renewal. I further provide a positive interlockingarrangement between the grounding switch andthe ratio adjusting switchsuch that the latter must definitely be in one of its tap operating orswitch closing positions 25 before the grounding switch can be operated.Moreover, I provide for the ratio adjusting switch a further improvedlocking means which is independent of the groundingswitch mechanism. Inorder to reduce the electrical hazard'ao of the electromagnet forlocking the grounding switch against operation while the transformer isenergized, I provide an improved grounding switch actuating mechanismwhich is mounted on the outside of the transformer casing so as to beisolated from the transformer proper and to be more convenientlyaccessible for inspection and maintenance.

My invention will be better understood from the following descriptionwhen considered in con- 40 nection with the accompanying three sheets ofdrawings, and its scope will be pointed out in the appended claims.

In the accompanying sheets of drawings, Fig. 1 represents inperspective, with part of the casing broken away. a transformerembodying my invention; Fig. 2 is a part perspective and a partdiagrammatic illustration-of a transformer switching arrangementembodying my invention as illustrated in Fig. 1; Fig. 3 is an elevationillustrating how certain contacts of my switching arrangement may beremoved for inspection and renewal; Fig. 4 is a perspective view partlyin section illustrating the isolated phase contact mounting for theterminal and grounding contacts of my switching arrangement; Fig. 5 is av perspective view with parts broken away illustrating my improvedgrounding switch actuat= ing mechanism; and Fig. 6 is a plan viewillustrating my improved arrangement for locking the ratio adjustingswitch handle independently of the grounding switch mechanism.

Referring now particularly to Figs. ii and 2, a liquid-immersed,self-cooled transformer is shown as having low-voltage windings iii,tapped high-voltage windings M, a ratio adjusting switch i2, and alsowithin the transformer casing E3, in accordance with my invention, agrounding switch it, contact means H5 for line terminals I6 connected tothe terminals of the high-voltage windings and engageable by thegrounding switch it, actuating means it for the grounding switch andinterlocked therewith actuating means it for the ratioadjusting switch,and eleetromagnetically controlled means it for preventing the closingof the grounding switch !4 while the transformer is energized. Furtherin accordance with my invention, for compactness, simplicity andaccessibility, the contact means i5, the grounding switch it and theratio adjusting switch it together with the actuating means for theseswitches are mounted on a suitable support such as the frame 9 withinthe easing l3, as more clearly shown in Figs. 1 and 3.

As shown, the contact means it comprises a pair of interconnectedcontacts for each phase of the circuit. Also as illustrated, thecontacts it are of the segmental garter-springsockettype,the

corresponding segments of each pair being interconnected by flexibleleads 2b in such a way that the forces produced by the circuit currentstend to increase the contact pressure. In Fig. 2, for simplicity, onlyone lead Zil is shown for each phase, but it is to be assumed that thereis an interconnecting lead for the corresponding segments of each pair,as shown more clearly in Fig. 4. For cooperating with each upper socketcontact l5, the line terminals iii are provided with plug contacts 2|which are suitably secured to the line feeder conductors 22, usuallycables, and the insulation tapered to form a bushing, as shown in Fig.3, in order to grade the voltage stresses.

In order that the contact means l5 of eachphase may be suitably isolatedand at the same time readily removable through the openings 23 in thetop of the transformer for inspection and maintenance, they may bemounted in an insulating cylinder 21 which is removably secured to asupporting cylinder 28. This may be of insulating material suitablyfastenedto the frame 9, as shown more clearly in Fig. 4. In order thatthe contacts l5 may be readily removable the cylinder 21 may be providedwith an inset metallic portion such as the threaded collar 29 whichscrews into a terminal ring 30 secured to the cylinder 28. The collar 29is so secured to the collar 21, by lugs and pins as shown for example,as 'to prevent relative movement. Similarly, the terminal ring 30 is sosecured to the cyl- The line terminals 96 withthe contacts 2| areinsertable in the upper contacts I5- inder 2b as to prevent relativemovement, for example by lugs and pins as shown, engaging a sleeve 30whichis rigidly secured to the cylinder 28. Each terminal ring 38 may beprovided with a suitable stud connector 32 to which the high voltagewindings M are connected. The seg-' ments of the contacts 55 aremaintained in proper alignment and the contacts suitably spaced bysleeves 33, 34 and 35, which may be of insulation. The inner connectors20 extend to the collar 29. The upper sleeve 35 may be secured to thecylinder 2i by pins as shown and may be tapered to fit the line terminalbushing. In order to remove the whole assembly within and including thecylinder 21, this cylinder may be provided with a metal collar 36 whichis suitably secured to the cylinder 21 and provided with suitable means,such as notches 31', which are engageable by projections on a T-wrench38 insertable through the openings 23 as shown in Fig. 3. observablethat the whole contact assembly is readily removable for inspection andrepairs and that a whole new unit may be quickly substituted for onewhich has outlived its usefulness. In order that the grounding switchcontacts 26 may likewise be readily removable, the supporting movablemember M for these contacts may be made of metal and tapped to receivethe lower threaded ends of the contacts 26. These contacts are providedwith a suitable enlarged portion which is engageable by the head of a T-wrench 39 insertable through the openings 23. Thus any one of thecontacts 26 can be readily removed and replaced without any necessityfor taking the transformer apart.

As shown, the actuating means for the grounding switch comprises anoperating member such as the crank 40 which is secured to the shaft l1,cranks 42 secured to the shaft 4!, and links 43 interconnecting thecranks 42 with the movable contact supporting member M of the groundingswitch. The member I4 is provided with guides 44 which slide in suitableguideways 45 in the frame 9.

In order to prevent operation of the grounding switch when open whilethe transformer is energized, I provide electromagnetically controlledmeans for preventing movement on the grounding switch actuatingmechanism if the transformer is energized. As shown, this meanscomprises an It will thus be ing member is arranged to engage a recessedportion associated with the operating shaft l'l. long as the magnetwinding 46 is energized to hold the locking member 41 in the lockingposition and the grounding switch is open, the crank 40 can not beturned in the direction of the arrow 48 to close the grounding switch.Upon 4168111 ergization of the magnet winding 46, the counter-' weightedarmature I 9 raises thelocking member 41 to release the shaft I'I sothat it can be rotated in the direction to close the grounding switch. U

While the locking mechanism. above described is generally satisfactory,it has the disadvantage of being completely within the transformercasing. It is therefore not conveniently accessible and themagnetwinding introduces an electrical hazard which is not desirable.Accordingly, I prefer, in accordance with my invention, to use theoperating handle mechanism shown in Fla-75 till purposes ofillustration.

amaova 5 because this mechanism is entirely self-contained and mountedexteriorly of the transformer. In this mechanism the crank or handielever is secured to a stub shaft it which is bifurcated at the inner endto engage a suitably flattened portion, not shown, on the shaft IT. Thestub shaft of each is provided with a projecting portion which may be inthe form of a cam so shaped as to be engaged by a locking member 5|mounted in the path of movement of the cam to the end connected to beactuated in response to the movement of the armature 52 of theelectromagnet 53. In Fig. 5, the locking member 5i is shown in thereleasing position, for clearness of illustration. This locking memberis rotatively mounted in the frame 5 3 of the operating mechanism andfor simplicity may be mounted to rock on its circular end portion in acorrespondingly shaped socket in the frame. The construction andarrangement of the parts is such that the locking member at is subjectedonly to compression when an attempt is made to turn the shaft in thedirection of the arrow 55 while the magnet id maintains the lockingmember raised into the locking position. The mechanism frame 5d issecured to the transformer casing ill by suitable means, such as boltstit, only one of which is indicated in Fig. 5. In order mechanicaly tolock the operating mechanism in either one of itstwo positions, theremay be provided a sliding bar loci: bl which is carried by the operatinglever it and is arranged to engage holes oil in the frame 56.Cooperating with the sliding bar lock Ell is an eye member 59 carried bythe operating lever it, and a padlock inserted through the eye in thismember and the eye in the member Ell serves to secure the switch ineither of its two positions so that the switch cannot be operated whilepadlocked. The connecting lead tt from the low voltage winding extendsthrough suitable insulation in the wall of the transformer casing 113and thence through the frame to the electromagnet it will accord inglybe clear that with the mechanism so ar= ranged any faults in the windingof the electro= magnet do not spread to the transformer and the wholemechanism is conveniently accessible without disturbing anything withinthe transformer.

The actuating mechanism tor the ratio adjusting switch i2 comprises acranlr. such as a handle lever 6i secured to the shaft ill, a shaft 62suitably geared to the shaft it and gears [63 and Lid for rotating themovable contacts d5 of the ratio adjusting switch into any one of thevarious on-tap positions, three being shown'tor The contacts E55 may bemounted within insulating cylinders designat ed by the number i2 in Fig.l. The handle lever 6i may, in accordance with my invention, include anextension 636 which is retractable in the part 63 and, as shown in Fig.6, a cover provided with pockets or recesses for so receiving one end orthe handle that the ratio adjusting switch must be in a definite on-tapposition before the cover bl] can be bolted in place against the side ofthe transformer casing it, the bolt holes for the cover being so spacedas to permit mounting the cover in only one way.

In order to prevent operation of the ratio adlusting switch l2 while thegrounding switch is open, I provide a positive interlock between theactuating means of these switches, such that, even when the groundingswitch actuating mechill in the cam it only when the grounding switch isin the grounding position.

Referring now to Fig. 2 for the operation of my invention, it will firstbe assumed that the transformer is energized and that the parts arepositioned as shown. If now for any reason it becomes desirable to workon the transformer either for inspection, renewal of parts or changingthe tap setting, it will first be necessary to deenergize thetransformer in order to release the lock F on the actuating mechanism ofthe grounding switch. The transformer is deenergized by opening thecircuit breaker in the feeder 22 at the supply station and opening thenetwork cir= cult breaker on the low voltage side of the transformer.The network circuit breaker and its associated relay mechanism may bemounted in a casing l5 secured to the transformer, as shown in Fig. 1.As soon as the transformer is deenergized, the electromagnet so nolonger retains its armature i9 and the adjustably mounted coun terweight'lti thereon raises the locking member ll from its recess on the shaftill. The operating crank to may then be turned in the direction of thearrow 68 to close the grounding switch. When the grounding switch isclosed, the notch it on the shaft li is in the plane of the cam it andthe shaft it? so that the actuating mechanism of the ratio adjustingswitch can be operated upon removal of the cover til. Accordingly, thetap position may be varied, but in any case some one of the notches 72must be definitely positioned in the plane of the earn it; otherwise, itwill not be possible to open the grounding switch.

' If it is desired to examine the contacts it or the contacts 2i; oi thegrounding switch, these may be removed in the manner heretoforedescribed and repairedii found necessary, or new ones substituted. It isto be noted that all this can be done without material disturbance tothe transformer, since it is merely necessary to remove the end bellsand the plate in order to gain access to the contacts i5 and 26.

While "i have shown and described my invention in considerable detail, ido not desire to be limited to the exact arrangements shown, but seal:to cover in the appended claims all those modifications that iali withinthe true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

l. in combination with a transformer and a casing therefor, a switchwithin said casing operative in one position to ground the high voltagewindingoi the transformer and means for actuating said switch mounted onthe outside of said casing and including an operating shaft extendingthrough said casing and means for preventing movement of said'shaft in adimotion. to move the switch to the grounding position while thetransformer is energized including an electromagnet connected to beenergized from the transformer, a projection on said shaft, a lockingmember mounted for of said casing and includingelectromagneticallycontrolled means energized from the transformer forpreventing actuation of the switching means to the grounding positionwhile the transformer is energized.

3. In combination with a transformer and a casing therefor, a switchwithin said casing operative in one position to ground the high voltagewinding of the transformer and means for actuating said switch mountedon the outside of said casing and including an operating member andmeans for preventing movement of said member in a direction to move theswitch to the grounding position when the transformer isenergized,'including an electromagnet connected to be energized from alow-voltage winding of the transformer.

i. In combination with a transformer and a casing therefor, a groundingswitch within said casing, an operating mechanism for said ground ingswitch mounted exteriorly of said casing and comprising a shaft, andmeans for preventing rotation of said shaft under a predeterminedcondition of the transformer including a projection on said shaft, amember movable in the plane of rotation of said projection andengageable thereby only under compression when the shaft is turned inone direction and the member is in a predetermined position andelectromagnetically controlled means for moving said member into saidposition connected to be energized from the transformer.

5. In combination with a polyphase transformer and a casing therefor, aframe mounted within said casing and switching means mounted on saidframe and comprising an isolated pair of interconnected contacts foreach phase,'each pair being respectively connected to a phase winding ofthe transformer, phase conductor terminal contacts respectivelyengageable with one of the contacts of each of said pairs, a groundingswitch comprising a movable bridging member of conducting materialconnected to ground, a contact for each phase mounted on said member andmeans for actuating said member to move the contacts mounted thereoninto engagement with the other contact of said pairs whereby to groundthe transformer windings connected thereto and said conductor terminals.

6. In combination with a polyphase transformer and a casing therefor, aframe mounted within said casing and switching means mounted onsaid-frame and comprising an isolated pair of interconnected contactsfor each phase, each pair being respectively connected to a phasewinding of the transformer, phase conductor terminal contactsrespectively engageable with one of the contacts of each of said pairs,a grounding switch comprising a movable member, a contact for each phasemounted on said member and grounded and means for actuating said memberto move the contacts mounted thereon into engagement with the othercontacts of said pairs whereby to ground the transformer windingsconnected thereto and said conductor terminals.

aocacrc 7. In combination with a polyphase transformer and a casingtherefor, a frame mounted within said casing and switching means mountedon said frame and comprising an isolated pair of interconnected contactsfor each phase, each pair being respectively connected to a phasewinding of the transformer, phase conductor terminal contactsrespectively engageable with one of the contacts of each of said pairs,at groundting switch comprising a movable bridging member of conductingmaterial connected to ground, a contact for each phase mounted on saidmember, means for actuating said member to move the contacts mountedthereon into engagement with the other contact of said pairs whereby toground the transformer windings connected thereto and said conductorterminals, means for preventing movement of said member while thetransformer is energized, a ratio adjusting switch connected to thetransformer windings which are connected to the pairs of contacts, meansfor actuating said ratio adjusting switch and means interlocking theactuating means for said member and the actuating means for said ratioadjusting switch for permitting actuation of the .ratio adjusting switchonly when the grounding lllll) switch is in the grounding position. 1'

8. In combination with a polyphase transformer and a casing therefor, aframe mounted within said casing and switching means mounted on saidframe and comprising an isolated pair of interconnected contacts foreach phase, each pair being respectively connected to a phase winding ofthe transformer, phase conductor terminal contacts respectivelyengageable with one of the contacts of each of said pairs, a groundingswitch comprising a grounded movable contact for each phase, means foractuating said movable contacts into engagement with the other contactof said pairs whereby to ground the transformer windings connectedthereto and said conductor terminals, means for preventing movement ofsaid grounding switch contacts while the transformer is energized, aratio adjusting switch connected to the transformer windings which areconnected to the pairs of contacts, means for actuating said ratioadjusting switch and means interlocking the actuating means for saidgrounding switch contacts and the actuating means for said ratioadjusting switch for permitting actuation of the ratio adjusting switchonly when the grounding switch contacts are in the grounding position.

9. In combination with a transformer and a casing therefor, switchingmeans mounted within said casing and comprising a pair of interconnectedcontacts connected to a winding of the transformer, a conductor terminalcontact insertable through said casing and engageable with one contactof said pair, a switch comprising a movable contact connected to groundand means for actuating said movable contact into engagement with theother contact of said pair whereby to ground the transformer windingconnected thereto and said conductor terminal, means for preventingmovement of said movable contact while the transformer is energized, aratio adjusting switch comprising actuating means therefor and meansinterlocking the actuating means for said movable contact and theactuating means for said ratio adjusting switch for permitting actuationof the ratio adjusting switch only when the movable contact is inengagement with the other contact of said pair.

10. In combination with a transformer and a casing therefor, switchingmeans mounted within aosaovo said casing and comprising a pair ofinterconnected contacts connected to a winding of the transformer, aconductor terminal contact insertable through said casing andengageable'with one contact of said pair, a switch comprising a movablecontact connected to ground and means for actuating saicl movablecontact into engagement with the other contact of said pair whereby toground the transformer winding connected thereto and said conductorterminal contact.

11. In combination with a transformer and a casing therefor, switchingmeans mounted within said casing and comprising contact means connectedto a winding of the transformer, a terminal contact insertable throughsaid casing and engageable with said contact means, a switch comprisinga movable contact connected to ground and means for actuating saidmovable contact into engagement with said contact means whereby toground the transformer winding connected thereto and said terminalcontact.

12. In combination with a transformer and a casing therefor, a readilyremovable housing supported within said casing and withdrawable throughan opening therein, contact means carried by said housing, a terminalcontact insertable through said casing opening to engage said contactmeans, a readily removable contact movably supported within said casingand engageable upon a predetermined movement in one direction with saidcontact means and means for removing said movable contact through saidcasing openmg.

13. In combination with a transformer and a casing therefor, a readilyremovable insulating housing supported within said casing andwithdrawable through an opening therein, two inter-' connected socketcontacts carried by said housing, a plug contact insertable through saidcasing opening to engage one of said socket contacts, .a readilyremovable plug contact movably supported within said casing andengageable upon a predetermined movement in one direction with the otherof said socket contacts and means for removing said movable plug contactthrough said casing opening subsequently to the removal of said housing.

14. In combination with a transformer and' a casing therefor, readilyremovable contact means supported within said casing and withdrawablethrough an opening therein, a terminal contact insertable through saidopening to engage said contact means, a readily removable contactmovably supported within said casing and engageable with said contactmeans on a predetermined movement in one direction and means forremoving said movable contact through said casing opening subsequentlyto the removal of said contact means.

15. In combination with a transformer and a casing therefor, a readilyremovable socket con tact means supported within said casing andwithdrawable through an opening therein and a cooperating plug contactinsertable through said casing opening to engage said socket contactmeans.

16. In combination with a transformer and a casing therefor, a readilyremovable socket contact means supported within said casing andwithdrawable through an opening therein, a. cooperating plug contactinsertable through said casing opening to engage said socket contactmeans, and a readily removable plug contact means removably supportedwithin said casing substantially in alignment with said cooperatingsocket and plug contact means and engageable with the socket contactmeans upon a predetermined movement in one direction.

17. In combination with a. transformer and a. casing therefor having acover provided with an opening, a readily removable socket contact meansinsertable through said cover opening and.

supported within said casing, and a cooperating plug contact insertablethrough said cover opening to engage said socket contact means.

18. In combination with a transformer and a casing therefor, readilyremovable contact means supported within said casing and withdrawablethrough an opening therein, a contact readily removable through saidopening movably sup ported within said casing and engageable with saidcontact means on a predetermined movement in one direction, and meansfor effecting the movement of said movable contact.

HAROLD R. TURNER.

